1. Field of the Invention
The present invention relates to a display device and, more particularly, to a liquid crystal display device provided with a liquid crystal display panel having an improved impact resistance and set in a resin frame formed by molding.
2. Description of the Related Art
A liquid crystal display device is a representative example of a display device. A liquid crystal display device includes a liquid crystal display panel and a driving circuit in combination, and is provided with a back light in case of need. The liquid crystal display panel is built by putting first and second substrates together with a liquid crystal layer held between the respective inside surfaces, namely, the major surfaces, of the first and the second substrate. Formed on the major surface of the first substrate are a plurality of scanning lines, and a plurality of data lines perpendicular to the scanning lines and isolated from the scanning lines by an insulating layer. Pixels are formed at the intersections of the scanning lines and the data lines, respectively. The pixels are arranged in a matrix to form a pixel area, namely, an effective display area. The scanning and the data lines are formed of a metal, preferably, aluminum. A plurality of color filters are formed on the inside surface of the second substrate. Normally, the color filters are red, green and blue filters. The first and the second substrate are put together, and peripheral gaps are sealed with a sealant.
FIG. 3 is a top view of a liquid crystal display panel PNL for a liquid crystal device, and FIG. 4 is a side view taken in the direction of the arrow A in FIG. 3. The PNL is formed by putting together two substrates SUB1 and SUB2 with their inside surfaces facing each other, and sealing a liquid crystal in a space between the substrates SUB1 and SUB2. These substrates SUB1 and SUB2 are thin glass plates. A plurality of scanning lines and a plurality of data lines perpendicular to the scanning lines and isolated from the scanning lines by an insulating layer are formed on the inside surface of the first substrate SUB1.
Generally, the two substrates SUB1 and SUB2 are put together in the following manner. The length of the right and the left side of the second substrate SUB2 is shorter than that of the right and the left side of the first substrate SUB1. The second substrate SUB2 is put on the first substrate SUB1 such that the upper, the right and the left side of the second substrate SUB2 are aligned with those of the first substrate SUB1, respectively, and the lower side of the second substrate SUB2 is on the inner side, the upper side as viewed in FIG. 3, of the lower side of the first substrate SUB1. Thus a lower part of the inside surface of the first substrate SUB1 is exposed. A scanning line driver chip DRV and a data line driving chip DRV provided with driving circuits are mounted on the exposed part of the first substrate SUB1. In FIG. 3, the scanning line driver chip DRV is on the left-hand side and the data line driver chip DRV is on the right-hand side.
Terminals of a flexible printed wiring board (flexible printed circuits) FPC are bonded to the exposed area of the liquid crystal display panel PNL on which the driver chips DRV are mounted, and then the four sides of the liquid crystal display panel PNL are fitted in grooves formed in a molded resin frame MLD. The flexible printed wiring board FPC is extended outside through an opening formed in the molded resin frame MLD. Recesses RET are formed in the four inner corners of the molded resin frame MLD to separate corner parts of the liquid crystal display panel PNL in which stress concentration is liable to occur to prevent the corner parts of the liquid crystal display panel PNL from cracking. A conventional liquid crystal display panel is provided in its four inner corners with the same recesses RET.
In an active matrix type liquid crystal display panel, thin-film transistors are formed in the vicinities of the intersections of the scanning lines and the data lines formed on a first substrate SUB1. Such a first substrate SUB1 is called also a thin-film transistor substrate. Color filters are formed on a second substrate SUB2 and hence the second substrate SUB2 is called a color filter substrate. Since the first substrate SUB1 and the second substrate SUB2 are thin glass plates, the first substrate SUB1 and the second substrate SUB2 crack and fissure easily when an external impact is applied thereto.
Methods of preventing cracking are disclosed in JP-A-2003-43469 (Patent document 1) and JP-A-11-231294 (Patent document 2). A method disclosed in Patent document 1 cuts off corner parts of a polarizing plate to prevent the formation of bubbles in the polarizing plate and to prevent the breakage of light-emitting diodes even if the glass substrates are chipped hot and humid conditions. A method disclosed in Patent document 2 puts a printed wiring board into close contact with the back surface of a liquid crystal display panel such that corners of the printed wiring board protrude outside from the edges of the liquid crystal display panel to prevent the direct application of shocks to the substrates of the liquid crystal display panel.